Conventionally, a working machine engine has been known that has: an engine body including a cylinder block section in which a cylinder is provided, a cylinder head section provided above the cylinder block section, and a crank case section provided below the cylinder block section; a crank shaft that is provided to allow the power transmission shaft of a working machine to be coupled thereto and rotatably supported by the crank case section; a casing that covers the outer surface of the engine body; a fan section that is coupled to the crank shaft and distributes air to cool the engine body by rotation of the crank shaft. A cooling air flow passage that allows cooling air to flow through by the fan section is provided between the engine body and the inner surface of the casing (see Patent Document 1).
There is a demand to improve the versatility of this kind of working machine engines, that is, a demand to be able to apply the same type of working machine engines to different kinds of working machines such as a brush cutter, chain saw, power blower and cultivator. When the power transmission shaft of a working machine is connected to one end of a crank shaft, the method of connecting one end of a crank shaft to the power transmission shaft of a working machine varies depending on the kind of a working machine, for example, whether or not the working machine needs a device such as a clutch for the connection. As a result of this, in order to improve the versatility of a working machine engine, it is required to secure space to connect a device such as a clutch in one end (herein after referred to as “the first end”) of the crank shaft to which the power transmission shaft of a working machine is coupled. Therefore, an engine has been proposed in which space is secured in the other end (hereinafter referred to as “second end”) opposite to the first end of the crank shaft by coupling an impeller as a blower means and a recoil starter into the second end of the crank shaft.